Mix ground beef with onion soup mix; set aside to rest as the onions are caramelized.
Add the butter to a skillet, when hot, add the onions and thyme and about 1/4 cup of water. Add lid and allow to simmer for three or four minutes until onions are tender are the water is nearly evaporated. (Check during cooking time to make sure all the water hasn’t evaporated early.) Remove lid and continue to cook, stirring often and adding a splash of water now and then if the onions are beginning to darken unevenly and stick to the pan. When onions are soft and beautifully browned, add dash of the brandy or Sherry and remove from heat.
Place a dent in the top of each burger so they’ll cook up flat and not rounded. Cook on the stovetop in a medium-hot pan or on the grill over medium-high heat, turning once, for about three minutes on the first side. Turn and add a spoonful of caramelized onions and a slice or two of cheese to the top of each burger, lower the heat to medium and continue to cook until burger is desired doneness, two to four minutes longer. Cover if needed, for a minute or two to get the cheese to melt.
In the meantime, brush the cut side of the buns with butter or oil and toast in a hot pan or on the grill.
Notes on temperature:
We like ours at 143 degrees F. which is just slightly pink in the middle.
If you need more or less than four burgers, for each burger:
For each burger:
Keywords: Beef, Burgers, Caramelized Onion, Cheese, french onion soup, Ground Beef, gruyere cheese, provolone, swiss cheese